Validate a JWS Signature

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.Validate, which validates exactly one signature, identified by a zero-based index, using the key configured at that same index.

var
success: Boolean;
jws: HCkJws;
jwsCompact: PWideChar;
base64Key: PWideChar;
v: Integer;

begin
success := False;

jws := CkJws_Create();

//  Load the JWS compact serialization.
jwsCompact := 'eyJhbGciOiJIUzI1NiJ9.VGhpcyBpcyB0aGUgY29udGVudCB0byBzaWduLg.<signature>';
success := CkJws_LoadJws(jws,jwsCompact);
if (success = False) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    Exit;
  end;

//  Provide the key for signature 0 (here an HMAC key).
base64Key := 'YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU=';
success := CkJws_SetMacKey(jws,0,base64Key,'base64');
if (success = False) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    Exit;
  end;

//  Validate the signature identified by the zero-based index, using the key configured at that index.
//  Validate returns 1 when the signature or MAC is cryptographically valid, 0 when it is not, or a
//  negative value on error.
v := CkJws_Validate(jws,0);
if (v < 0) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    Exit;
  end;
if (v <> 1) then
  begin
    Memo1.Lines.Add('The signature is not valid.');
    Exit;
  end;
Memo1.Lines.Add('The signature is valid.');

CkJws_Dispose(jws);